Acoustic diagnostics of hydrophysical variability on Abkhazian shelf of the Black Sea

The results of observation of the variability of marine environment by acoustic and contact methods on the Abkhazian shelf of the Black Sea are presented. Russian-Abkhazian scientific cooperation have been supported by RFBR since 2013. The main goal of the research was to study the dynamics of the coastal waters of the shelf with a steep slope in conditions of spring-summer stratification. Measurements were carried out on a stationary track in the coastal zone by the method of acoustic autogeneration (Furduev's method), but the main part of data was obtained by ADCP «Rio Grande 600 kHz» acoustic Doppler profilometer, which was fixed at trestle. Also, in various sections of shelf were made spatial surveys with ADCP installed on a small motor vessel. Representative data of currents direction in coastal waters, their variability in water bulk and in time, as well as vertical structure of sound velocity and temperature were obtained. The material on temporal and spatial (in vertical) variability of backscattering acoustic signal, which provides information about water contamination, was also obained. Particular attention was paid to the investigation of internal waves, which, in addition to measurements by an acoustic profilometer, were also recorded by anchored vertical thermistor chains. Short-period (from units to tens of minutes) and long-period oscillations of the thermocline with a period close to the inertial one were recorded. The features of internal waves which propagate close to the shore were revealed. Special studies to monitor the coastal currents were conducted in the areas of the Gumista and Kodor rivers flowing into the sea.